In general, motors with a structure that a rotary shaft of the motor rotates just in one direction and is prevented from rotating in another direction, namely, in the reverse direction are needed in various fields. For instance, induction motors which are used in sporting goods, such as electronic bicycles or running machines, hybrid vehicles, and others need rotary shafts of the motors which are prevented from rotating in the reverse direction. Therefore, various forms of the motor structure for preventing the reverse rotation have been disclosed.
The representative structure for preventing the reverse rotation is a structure to stop rotation of the motor using a reverse rotation sensing circuit at the time that the rotary shaft rotates in the reverse direction. As a technology that does not use the reverse rotation sensing circuit, Korean Patent No. 10-0619783 discloses a hybrid induction motor with a reverse rotation prevention function. In Korean Patent No. 10-0619783, the hybrid induction motor includes a one-way bearing which has an outer wheel and an inner wheel, and only the inner wheel rotates at the time of one-way rotation but all of the inner wheel and the outer wheel rotate together at the time of reverse rotation. A rotary shaft of the motor is joined to the inner wheel of the one-way bearing and a pin is mounted to the outer wheel of the one-way bearing, such that when the outer wheel rotates at the time of the reverse rotation of the rotary shaft, the pin presses a power-down switch and the pin mounted on the outer wheel returns to its original position by elasticity of a returning spring, so as to prevent the reverse rotation of the rotary shaft of the motor.
According to the structure disclosed in Korean Patent No. 10-0619783, the induction motor has several problems in that it can prevent the reverse rotation of the rotary shaft of the motor but cannot prevent a minute reverse rotation that the pin mounted on the outer wheel of the one-way bearing moves to the power-down switch, and in that it is complicated in structure because it needs the power-down switch or the returning spring.
Therefore, in order to overcome the above-mentioned problems, the inventors of the present invention propose a motor with a new structure that can prevent the reverse rotation of the rotary shaft of the motor through a simple structure.